Prepare repo for rosdistro release

[mfaferek93]

Summary

Prepare all packages for first-time release to rosdistro (Jazzy, Ubuntu 24.04). Several blockers need to be resolved before bloom-release can succeed on the ROS build farm.

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Proposed solution (optional)

1. Vendor tl::expected and jwt-cpp in gateway

ros2_medkit_gateway fetches both via CMake FetchContent at build time. The ROS build farm has no internet access - this will fail.

Both are header-only - vendor into src/ros2_medkit_gateway/src/vendored/, replace FetchContent blocks with local target_include_directories.

• tl::expected v1.3.1 (Boost Software License) - https://github.com/TartanLlama/expected
• jwt-cpp v0.7.0 (MIT) - https://github.com/Thalhammer/jwt-cpp

2. Add missing libssl-dev to gateway package.xml

CMakeLists.txt:42 has find_package(OpenSSL REQUIRED) but package.xml doesn't declare the dependency. One-liner:

<depend>libssl-dev</depend>

3. Generate CHANGELOG.rst for all 6 packages

Required by catkin_prepare_release. Run catkin_generate_changelog --all, clean up entries.

4. Set up ros2-gbp release infrastructure

1. Create GitHub PAT (public_repo + workflow), save to ~/.config/bloom
2. File "New Release Team" issue at ros2-gbp/ros2-gbp-github-org
3. Submit source entry PR to ros/rosdistro jazzy/distribution.yaml
4. bloom-release --new-track --rosdistro jazzy --track jazzy ros2_medkit

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Additional context (optional)

• All 6 packages are in a monorepo - single bloom-release invocation covers all
• dynmsg vendoring (f3d0383) eliminated the need for phased release
• All rosdep keys verified OK: nlohmann-json-dev, libcpp-httplib-dev, sqlite3, yaml_cpp_vendor
• Ref: https://docs.ros.org/en/jazzy/How-To-Guides/Releasing/First-Time-Release.html